Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
int h,w;
char a[55][55];
int d[55][55];
int dx[]={1,0,-1,0};
int dy[]={0,-1,0,1};
int main()
{
	cin>>h>>w;
	int cnt=0;
	memset(a,'#',sizeof a);
	for(int i=1;i<=h;++i)
	for(int j=1;j<=w;++j)
	{
		cin>>a[i][j];
		if(a[i][j]=='#')
			cnt++;
	}
	queue<pair<int,int> > q;
	q.push({1,1});
	memset(d,-1,sizeof d);
	d[1][1]=0;
	while(!q.empty())
	{
		pair<int,int> t = q.front();
		q.pop();
		int tx=t.first;
		int ty=t.second;
		for(int i=0;i<4;++i)
		{
			int nx = tx+dx[i];
			int ny = ty+dy[i];
			if(a[nx][ny]=='#')
				continue;
			if(d[nx][ny]!=-1)
				continue;
			d[nx][ny]=d[tx][ty]+1;
			q.push({nx,ny});
		}
	}
	if(d[h][w]==-1)
		cout<<-1<<endl;
	else
		cout<<w*h-cnt-d[h][w]-1<<endl;
}